/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 2000-2002,2004,2005 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.sun.org.apache.xml.internal.serialize;

import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.io.Writer;
import com.sun.org.apache.xerces.internal.util.EncodingMap;

/**
 * This class represents an encoding.
 *
 * @version $Id: EncodingInfo.java,v 1.6 2007/10/18 03:39:08 joehw Exp $
 */
public class EncodingInfo {

  // An array to hold the argument for a method of Charset, CharsetEncoder or CharToByteConverter.
  private Object[] fArgsForMethod = null;

  // name of encoding as registered with IANA;
  // preferably a MIME name, but aliases are fine too.
  String ianaName;
  String javaName;
  int lastPrintable;

  // The CharsetEncoder with which we test unusual characters.
  Object fCharsetEncoder = null;

  // The CharToByteConverter with which we test unusual characters.
  Object fCharToByteConverter = null;

  // Is the converter null because it can't be instantiated
  // for some reason (perhaps we're running with insufficient authority as
  // an applet?
  boolean fHaveTriedCToB = false;

  // Is the charset encoder usable or available.
  boolean fHaveTriedCharsetEncoder = false;

  /**
   * Creates new <code>EncodingInfo</code> instance.
   */
  public EncodingInfo(String ianaName, String javaName, int lastPrintable) {
    this.ianaName = ianaName;
    this.javaName = EncodingMap.getIANA2JavaMapping(ianaName);
    this.lastPrintable = lastPrintable;
  }

  /**
   * Returns a MIME charset name of this encoding.
   */
  public String getIANAName() {
    return this.ianaName;
  }

  /**
   * Returns a writer for this encoding based on
   * an output stream.
   *
   * @return A suitable writer
   * @throws UnsupportedEncodingException There is no convertor to support this encoding
   */
  public Writer getWriter(OutputStream output)
      throws UnsupportedEncodingException {
    // this should always be true!
    if (javaName != null) {
      return new OutputStreamWriter(output, javaName);
    }
    javaName = EncodingMap.getIANA2JavaMapping(ianaName);
    if (javaName == null)
    // use UTF-8 as preferred encoding
    {
      return new OutputStreamWriter(output, "UTF8");
    }
    return new OutputStreamWriter(output, javaName);
  }

  /**
   * Checks whether the specified character is printable or not in this encoding.
   *
   * @param ch a code point (0-0x10ffff)
   */
  public boolean isPrintable(char ch) {
    if (ch <= this.lastPrintable) {
      return true;
    }
    return isPrintable0(ch);
  }

  /**
   * Checks whether the specified character is printable or not in this encoding.
   * This method accomplishes this using a java.nio.CharsetEncoder. If NIO isn't
   * available it will attempt use a sun.io.CharToByteConverter.
   *
   * @param ch a code point (0-0x10ffff)
   */
  private boolean isPrintable0(char ch) {

    // Attempt to get a CharsetEncoder for this encoding.
    if (fCharsetEncoder == null && CharsetMethods.fgNIOCharsetAvailable
        && !fHaveTriedCharsetEncoder) {
      if (fArgsForMethod == null) {
        fArgsForMethod = new Object[1];
      }
      // try and create the CharsetEncoder
      try {
        fArgsForMethod[0] = javaName;
        Object charset = CharsetMethods.fgCharsetForNameMethod.invoke(null, fArgsForMethod);
        if (((Boolean) CharsetMethods.fgCharsetCanEncodeMethod.invoke(charset, (Object[]) null))
            .booleanValue()) {
          fCharsetEncoder = CharsetMethods.fgCharsetNewEncoderMethod
              .invoke(charset, (Object[]) null);
        }
        // This charset cannot be used for encoding, don't try it again...
        else {
          fHaveTriedCharsetEncoder = true;
        }
      } catch (Exception e) {
        // don't try it again...
        fHaveTriedCharsetEncoder = true;
      }
    }
    // Attempt to use the CharsetEncoder to determine whether the character is printable.
    if (fCharsetEncoder != null) {
      try {
        fArgsForMethod[0] = new Character(ch);
        return ((Boolean) CharsetMethods.fgCharsetEncoderCanEncodeMethod
            .invoke(fCharsetEncoder, fArgsForMethod)).booleanValue();
      } catch (Exception e) {
        // obviously can't use this charset encoder; possibly a JDK bug
        fCharsetEncoder = null;
        fHaveTriedCharsetEncoder = false;
      }
    }

    // As a last resort try to use a sun.io.CharToByteConverter to
    // determine whether this character is printable. We will always
    // reach here on JDK 1.3 or below.
    if (fCharToByteConverter == null) {
      if (fHaveTriedCToB || !CharToByteConverterMethods.fgConvertersAvailable) {
        // forget it; nothing we can do...
        return false;
      }
      if (fArgsForMethod == null) {
        fArgsForMethod = new Object[1];
      }
      // try and create the CharToByteConverter
      try {
        fArgsForMethod[0] = javaName;
        fCharToByteConverter = CharToByteConverterMethods.fgGetConverterMethod
            .invoke(null, fArgsForMethod);
      } catch (Exception e) {
        // don't try it again...
        fHaveTriedCToB = true;
        return false;
      }
    }
    try {
      fArgsForMethod[0] = new Character(ch);
      return ((Boolean) CharToByteConverterMethods.fgCanConvertMethod
          .invoke(fCharToByteConverter, fArgsForMethod)).booleanValue();
    } catch (Exception e) {
      // obviously can't use this converter; probably some kind of
      // security restriction
      fCharToByteConverter = null;
      fHaveTriedCToB = false;
      return false;
    }
  }

  // is this an encoding name recognized by this JDK?
  // if not, will throw UnsupportedEncodingException
  public static void testJavaEncodingName(String name) throws UnsupportedEncodingException {
    final byte[] bTest = {(byte) 'v', (byte) 'a', (byte) 'l', (byte) 'i', (byte) 'd'};
    String s = new String(bTest, name);
  }

  /**
   * Holder of methods from java.nio.charset.Charset and java.nio.charset.CharsetEncoder.
   */
  static class CharsetMethods {

    // Method: java.nio.charset.Charset.forName(java.lang.String)
    private static java.lang.reflect.Method fgCharsetForNameMethod = null;

    // Method: java.nio.charset.Charset.canEncode()
    private static java.lang.reflect.Method fgCharsetCanEncodeMethod = null;

    // Method: java.nio.charset.Charset.newEncoder()
    private static java.lang.reflect.Method fgCharsetNewEncoderMethod = null;

    // Method: java.nio.charset.CharsetEncoder.canEncode(char)
    private static java.lang.reflect.Method fgCharsetEncoderCanEncodeMethod = null;

    // Flag indicating whether or not java.nio.charset.* is available.
    private static boolean fgNIOCharsetAvailable = false;

    private CharsetMethods() {
    }

    // Attempt to get methods for Charset and CharsetEncoder on class initialization.
    static {
      try {
        Class charsetClass = Class.forName("java.nio.charset.Charset");
        Class charsetEncoderClass = Class.forName("java.nio.charset.CharsetEncoder");
        fgCharsetForNameMethod = charsetClass.getMethod("forName", new Class[]{String.class});
        fgCharsetCanEncodeMethod = charsetClass.getMethod("canEncode", new Class[]{});
        fgCharsetNewEncoderMethod = charsetClass.getMethod("newEncoder", new Class[]{});
        fgCharsetEncoderCanEncodeMethod = charsetEncoderClass
            .getMethod("canEncode", new Class[]{Character.TYPE});
        fgNIOCharsetAvailable = true;
      }
      // ClassNotFoundException, NoSuchMethodException or SecurityException
      // Whatever the case, we cannot use java.nio.charset.*.
      catch (Exception exc) {
        fgCharsetForNameMethod = null;
        fgCharsetCanEncodeMethod = null;
        fgCharsetEncoderCanEncodeMethod = null;
        fgCharsetNewEncoderMethod = null;
        fgNIOCharsetAvailable = false;
      }
    }
  }

  /**
   * Holder of methods from sun.io.CharToByteConverter.
   */
  static class CharToByteConverterMethods {

    // Method: sun.io.CharToByteConverter.getConverter(java.lang.String)
    private static java.lang.reflect.Method fgGetConverterMethod = null;

    // Method: sun.io.CharToByteConverter.canConvert(char)
    private static java.lang.reflect.Method fgCanConvertMethod = null;

    // Flag indicating whether or not sun.io.CharToByteConverter is available.
    private static boolean fgConvertersAvailable = false;

    private CharToByteConverterMethods() {
    }

    // Attempt to get methods for char to byte converter on class initialization.
    static {
      try {
        Class clazz = Class.forName("sun.io.CharToByteConverter");
        fgGetConverterMethod = clazz.getMethod("getConverter", new Class[]{String.class});
        fgCanConvertMethod = clazz.getMethod("canConvert", new Class[]{Character.TYPE});
        fgConvertersAvailable = true;
      }
      // ClassNotFoundException, NoSuchMethodException or SecurityException
      // Whatever the case, we cannot use sun.io.CharToByteConverter.
      catch (Exception exc) {
        fgGetConverterMethod = null;
        fgCanConvertMethod = null;
        fgConvertersAvailable = false;
      }
    }
  }
}
